Question: If $a + b + c = 4$ and $x + y = -3$, what is $9a + 5x + 9b + 9c + 5y$ ?
$= 9a + 9b + 9c + 5x + 5y$ $= (9) \cdot (a + b + c) + (5) \cdot (x + y)$ $= (9) \cdot (4) + (5) \cdot (-3)$ $= 36 - 15$ $= 21$